Sea wall and its sustainability
6 likes5,147 views
1. There are three main types of seawalls: vertical, curved, and mound. Vertical seawalls are the easiest to design and construct but can become undermined. Curved seawalls reduce wave reflection and turbulence but are more complex to design. Mound seawalls provide maximum wave energy dissipation but are less durable and have a shorter lifespan. 2. Several seawall systems are described: gravity walls, L-shaped walls with buttresses, and systems that use piles or diaphragm walls to provide support independently of soil weight. Pile-supported systems are less vulnerable to scour but more expensive. Diaphragm systems are flexible and independent of soil surcharge weight.
More Related Content
Similar to Sea wall and its sustainability (20)
Sea wall and its sustainability
- 1. Seawalls and its sustainability Presented by Shravan sharma FRM MA-2 07
- 2. Introduction • Coastal defence structure – hard stabilization • Along the coast • Reinforced concret , boulders, steel, gabions, aluminium ,
- 3. Types 1. Vertical 2. Curved 3. Mound
- 4. Most easy designing and construction Deflect waves ,loose rubbles absorb energy Advantages Disadvantages 1. Can be under cut by high wave energy environment 2. Not efficient in long term 3. Prone to expensive damage Vertical type
- 5. Advantage 1. Prevent overtopping the w 2. low reflected waves and much 3. reduced turbulence Disadvantage 1.More complex design process. 2.can scour material at the base of the wall causing them to become undermined Round type
- 6. Advantages 1.Current designs use porous designs of rock, concrete armour. 2.Slope and loose material ensure maximum dissipation of wave energy. 3.Lower cost option Disadvantages 1.Less durable. 2.Shorter life expectancy. 3.Cannot withstand or protect from high-energy conditions effectively Mound type
- 7. Functions Primary functions Accessory function • Retaining soil and surcharge loads behind wall . • Protection of shoreline from wave loads • Protect frontline beaches from storm surges, shoreline erosion and wave overtopping. • Habitate for a variety of fauna
- 8. Design consideration • Direct wave force action • Uplift force imposed by wave action • Wave overtopping • Storm surge • Toe scour
- 9. • The uplift force imposed by wave action is an important factor that is frequently neglected by design professionals . • Leads to instability and undermines the longevity of the Sea Wall structure
- 11. Stepped sea wall
- 13. Sea Wall Systems • System A: Gravity Wall • System B: L-Shaped Wall with Buttresses • System C: L-Shaped Wall with Buttresses Supported by Piles • System D: Diaphragm Wall System with Horizontally Spun Wall • System E: Soldier Pile System with Horizontally Spun Wall and Tie Back Anchors (Modified Bulkhead Approach)
- 14. System A: Gravity Wall • It is extremely costly to build, especially when wall height dictates significant development of the wall base • Requires consideration of significant wave generated uplift force • Relies heavily upon the weight of the wall when that weight significantly decreases due to buoyancy effect
- 15. continue • Requires a very stiff base that can prevent wall settlement, tilting or heavy toe scour that affects wall integrity and stability. • Unviable option when bedrock elevation or elevation of other suitable base significantly varies along the wall length.
- 16. System B: L-Shaped Wall with Buttresses • More economical than a Gravity Wall and easier to construct. • Buttress of the wall serves as a stiffening element for the wall itself, and allows some force redistribution in the wall based upon the stiffness of the tapered buttress element • Same design stability issues as a Gravity Wall:Significant wave generated uplift force.
- 17. Continue • Heavy reliance on soil surcharge on the hill of the wall at the time when that weight significantly decreases due to buoyancy. • Requirement for very stiff base and possibility of heavy scour that can affect wall stability
- 18. System C: L-Shaped Wall with Buttresses Supported by Piles • A type of wall, a modification of System B, that has a significant advantage over System B. • Does not rely, or relies much less, on the gravity of the hill surcharge. • Less susceptible to distress due to scour problem. • Stability of the wall depends upon the pile capacity to resist uplift and the effect of horizontal load.
- 19. Continue Price of the wall can be prohibitive
- 20. System D: Diaphragm Wall System with Horizontally Spun Wall • Easy to construct • Lower cost of construction and more flexibility of the system, as compared to the same features of traditional designs. • Wall stability is not dependent on the gravity load of backfill. • Wall stability is independent of gravity of the surcharge.
- 21. Continue • Low effect of soil scour in front of the wall on wall system distress. Easy maintenance. • Lack of uplift pressure on the wall base or heel, as the Diaphragm system does not have a heel. • Horizontally spun continuous wall supported by Deep Beam Diaphragms. Wall Diaphragm provides support for loads applied in both directions
- 24. System E: Soldier Pile System with Horizontally Spun Wall and Tie Back Anchors (Modified Bulkhead Approach • easy to construct. • The front of is similar to the front wall of the D system • Design philosophy is not same
- 30. Continue • Elastic foundation to resist the wave load in landward direction.
- 31. Continue • Lack of uplift pressure on the wall base. • Stiffness of the soil anchors and stiffness of specially modified backfill allows for the design of the retaining wall as a continuously spun horizontally slab.
- 32. • Wall stability is not dependent on the gravity load of backfill. • Low effect of soil scour in front of the wall on wall system distress. • Easy maintenance. • Lower cost of construction and higher adaptability
- 33. Advantage of system D and E • The erosion of the soil around the front pile can be easily remedied • Use of flowable fly ash fill that can easily restore eroded soil around the pile to a preexisting or better condition. • Erosion is almost never critical and does not require urgent attention and can be restored during normal beach nourishment operations.
- 34. Issues… 1. Sea level rise 2. Modelling limitation
- 35. Conclusion • Control coastal erosion . • Long term – hard stabilization • Maintenance is needed • Cost –effective approach is recommended • Unintentional harm to unprotected near by shores
- 36. Reference cited • Vitaly B. Feygin ,Sea Wall Systems Structural Engineering magazine USA. • Yoshimi goda , Random seas and design of maritime structures ; 3rd edition • www.channelcoast.org